Thomas was of noble birth; after being ordained at Lyon, c. 1245, he continued his studies in France at Orléans and Paris. He then taught canon law at Paris and at Oxford, where in 1262 he became chancellor. When Simon de Montfort (Montfort, Simon de, Earl Of Leicester), Earl of Leicester, won the Barons' War (1264), he appointed Thomas chancellor of England in 1265. After Montfort's death on the following August 4 and after the baronial party's subsequent disintegration, Thomas was dismissed and returned to Paris (1265–72). He was then at Oxford for a second term as chancellor (1273–74). Known for his ascetic life, strict discipline, and martial spirit, he was made (1275) bishop of Hereford, which he found in a state of deterioration. He restored his see, began a reform, and became adviser to King Edward I of England.

After John Peckham became archbishop of Canterbury in 1279, Thomas became involved in jurisdictional disputes with him that led to his excommunication in 1282. He went to Italy to plead his cause to Pope Martin IV but died before his case was judged. After Thomas was buried in the cathedral of Hereford, several miracles were reported, and Edward requested the process for his veneration. He was canonized by Pope John XXII.